A woman, nude and asleep; a man, seated beside her, smoking a cigarette in pensive silence as morning light glares through the window. The texture of the image is grainy and ”real,” yet there’s a tantalizing stark lyricism to the enigmatic opening shot of 21 Grams. Immediately, we recognize Sean Penn and his cool aura of sullen experience. Yet who, exactly, are these two lovers, with their luminous, ominous vibe? ”21 Grams” is a movie in which even the quietest moments are tantalizingly alive with hidden meaning. They’re disconnected slivers of reality, and the movie beckons the audience to put them back together.

Directing his first English-language feature, the spellbinding Mexican filmmaker Alejandro González Iñárritu (”Amores Perros”) glides back and forth between past and present, slicing time as if it were a ribbon. Here’s Penn in a hospital, arms laced with tubes, and here’s Naomi Watts, the woman who was asleep beside him, speaking at a recovery meeting and then, moments later (but really earlier), in the middle of a drug binge. Here’s Benicio Del Toro as a youth counselor with tattoos up to his neck, giving testament to God’s power moments before he lashes out, with what might be the devil’s wrath, at the thug he’s advising. Here’s a nice husband (Danny Huston) and his two young daughters, cell-phoning his wife from a mall diner, and here are Del Toro, Watts, and a blood-soaked Penn enacting some violent deliverance in a dank hotel room. And here’s Penn, once again, now being handed a jar that contains…his heart.

”21 Grams” is like a mirror that’s been smashed into 1,000 shards and reassembled by Iñárritu piece by glittery piece. That he does it with the solemnly hypnotic skill of a born showman makes the movie the latest example of what might be called an Art Ride. Here, as in ”Pulp Fiction” and ”Memento,” events are fractured and overlapped, so that even the most random catastrophe – like, say, a hit-and-run accident that leaves a trio of innocents dead in the road – acquires the dark aura of inevitability. A hush of impending cataclysm hovers over ”21 Grams,” which wants to be a parable of love, death, birth, loss, vengeance, and (you guessed it) salvation. The title refers to nothing less than the weight of the soul.

It’s a startlingly crafted movie, with several extraordinary performances, and as long as we’re putting it together in our heads, trying to puzzle out what these disparate characters have to do with one another, we’re held in the grip of Iñárritu’s somber passion. As a woman coping with impossible tragedy, Watts digs to primal levels of bereavement and rage; she acts with a wounding force. Del Toro, hushed, implosive, and totemic in his anger, does his boldest work yet as an ex-con who has embraced Jesus with such a guilty fervor that even his attempts to be a good man are laced with burning sociopathology. Penn, considering the extreme circumstances (which I won’t reveal) that surround his character, grounds the movie with his hipster hostility.

Yet for all its lurches toward greatness, ”21 Grams” is, paradoxically, a movie that loses power the more you perceive what’s actually going on in it. Laid end to end, the story is, to put it mildly, overwrought, fusing several cataclysms too many. It’s a testament to Iñárritu’s skill that he keeps you absorbed as intensely as he does. It’s a measure of his pretensions that you leave ”21 Grams” at once overwhelmed and exhausted, eager to see him apply his wizardry to a tale that didn’t depend on being obscured by it.